Semiconductor Structure and Manufacturing Method Thereof

ABSTRACT

A semiconductor structure includes a three dimensional stack including a first semiconductor die and a second semiconductor die. The second semiconductor die is connected with the first semiconductor die with a bump between the first semiconductor die and the second semiconductor die. The semiconductor structure includes a molding compound between the first semiconductor die and the second semiconductor die. A first portion of a metal structure over a surface of the three dimensional stack and contacting a backside of the second semiconductor die and a second portion of the metal structure over the surface of the three dimensional stack and configured for electrically connecting the three dimensional stack with an external electronic device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/061,615, filed on Oct. 23, 2013, and entitled “SemiconductorStructure and Manufacturing Method Thereof”, which application is hereinincorporated herein in its entirety by reference.

BACKGROUND

Chip scale packages (CSP) are widely adopted for semiconductor chipassemblies in the industry because the component has a smaller size. Apopular methodology of manufacturing a CSP component is a technologycalled surface mounting technology (SMT). The surface mountingtechnology is a method in which the semiconductor chip is mounted orplaced directly on the surface of a printed circuit board (PCB). Asemiconductor component made with SMT usually has either smaller bondingwires or no bonding wires at all.

Semiconductor chip enclosed in the chip scale component includesthousands of transistors and other miniaturized devices. The circuitrydensity keeps increasing as technology capability migrates from micronto nano scale. With a down-trending size, electronic products becomemore and more popular because its functionality and weight can fit indifferent occasions and applications.

However, heat generation in the packaged semiconductor component isdiscovered to be a drawback while people are celebrating the achievementof multi-chip stack package. Gaps in the three dimensional structure ofa multi-chip stack are filled with materials like molding compound orother CTE match layer that traps heat inside the package. Undesiredoverheating is observed to be one of the major root causes of componentmalfunction. Some solutions such as adding fan or other external coolingto the component are implemented but still can not resolve the issue.Hence, a methodology to improve heat dissipation is still to be sought.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isemphasized that, in accordance with the standard practice in theindustry, various features are not drawn to scale. In fact, thedimensions of the various features may be arbitrarily increased orreduced for clarity of discussion.

FIG. 1 is a cross sectional view of a semiconductor structure with dummymetal structure for dissipating heat in accordance with some embodimentsof the present disclosure.

FIG. 2 is an enlarged view of the dummy metal structure and dummy bumpin FIG. 1 including in accordance with some embodiments of the presentdisclosure.

FIG. 3 is a cross sectional view of a dummy metal structure and a dummybump in contact with a heat sink in accordance with some embodiments ofthe present disclosure.

FIG. 4 is a cross sectional view of a dummy metal structure and a dummybump in contact with a dummy heat conductive trace on a PCB inaccordance with some embodiments of the present disclosure.

FIG. 5 is a flow chart diagram of a method for manufacturing asemiconductor structure in accordance with some embodiments of thepresent disclosure.

FIG. 6A to FIG. 6K are cross sectional views of a semiconductorstructure at different operation stage in accordance with someembodiments of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

The manufacturing and use of the embodiments are discussed in detailsbelow. It should be appreciated, however, that the embodiments providemany applicable inventive concepts that can be embodied in a widevariety of specific contexts. It is to be understood that the followingdisclosure provides many different embodiments or examples forimplementing different features of various embodiments. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting.

Further, it is understood that several processing steps and/or featuresof a device may be only briefly described. Also, additional processingsteps and/or features can be added and certain of the followingprocessing steps and/or features can be removed or changed while stillimplementing the claims. Thus, the following description should beunderstood to represent examples only, and are not intended to suggestthat one or more steps or features is required.

In addition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

In the present disclosure, a heat dissipation structure is disposed on asemiconductor device to facilitate transferring thermal energy from thesemiconductor device to ambient air. In some embodiments, thesemiconductor device is in a chip-on-chip (COC) semiconductor structure,which is an integrated three dimensional stack of multiple semiconductorchips or dies. Heat generated inside the semiconductor device isdispelled by the heat dissipation structure disposed on a passivesurface of the semiconductor device. The heat dissipation structure isfabricated to utilize some dummy conductive components without affectingdevice performance.

As used herein, “vapor deposition” refers to operations of depositingmaterials on a substrate using a vapor phase of a material to bedeposited or a precursor of the material. Vapor deposition operationsinclude any operations such as, but not limited to, chemical vapordeposition (CVD) and physical vapor deposition (PVD). Examples of vapordeposition methods include hot filament CVD, rf-CVD, laser CVD (LCVD),conformal diamond coating operations, metal-organic CVD (MOCVD),sputtering, thermal evaporation PVD, ionized metal PVD (IMPVD), electronbeam PVD (EBPVD), reactive PVD, atomic layer deposition (ALD), plasmaenhanced CVD (PECVD), high density plasma CVD (HDPCVD), low pressure CVD(LPCVD), and the like.

As uses herein, a “passive surface” refers to a surface of asemiconductor chip or die that is not configured to have any electricalterminal or contact for its normal operation. For example, for asemiconductor die, the passive surface is referred to a backside of thesemiconductor die. Instead, an “active surface” is a surface includingelectrical terminal or contact for electrical connecting with anexternal circuit or device. In some embodiments, the active surface hasmetal pads exposing through a protective dielectric layer on top of thedie. The metal pads are extension of internal circuitry of the die anddesigned to be coupled with a conductive material such as metal wire,conductive trace during post end packaging operation.

FIG. 1 is a semiconductor structure 100. In some embodiments, thesemiconductor structure 100 is three dimensional. The semiconductorstructure 100 includes at least two independent semiconductor devicesthat are assembled altogether to form a stack. The independentsemiconductor devices are connected by a bump 120. One of theindependent semiconductor devices has a substrate 150 with a circuitrydisposed thereon. The circuitry includes components like metal pads 106,conductive trace 108 formed on a surface of the substrate 150.

In some embodiments, the substrate 150 is a semiconductor chip or diethat has a substrate and some embedded devices such as MOSFET. Thesubstrate refers to a bulk semiconductor substrate on which variouslayers and device structure are formed. In some embodiments, the bulksubstrate includes silicon or a compound semiconductor, such as Ga As,InP, Si/Ge, or SiC. Examples of the layers include dielectric layers,doped layers, polysilicon layers or conductive layers. Examples of thedevice structures include transistors, resistors, and/or capacitors,which may be interconnected through an interconnect layer to additionalintegrated circuits.

A dielectric layer 110 disposed on the substrate 150 surrounds metal pad106. The metal pad 106 provides a connection between internal conductivetraces in the substrate and the conductive trace 108. In someembodiments, metal pad 106 is also a portion of the top metal layer ofinternal conductive traces in the substrate. The dimension of metal pad106 is determined during top metal etch and an additional etch operationis introduced to expose the metal pad 106 by removing a portion of thedielectric layer 110. Metal pad 106 is made with electrical conductivematerial such as Au, Ag, Cu, Al, or alloy thereof.

Conductive trace 108 electrically connecting the substrate 105 withanother device. In some embodiments, the conductive trace 108 is aredistribution layer (RDL) for a fan-in or fan-out configuration toredirect electrical current. In some embodiments, the conductive trace108 is a post passivation inductor (PPI). In a two mask (2M) technology,a portion of the PPI is also designed to receive the bump 120 as shownin FIG. 1. In some other embodiments, the conductive trace 108 isfabricated with a four mask (4M) technology and therefore some extrametal structures such as under bump metal (UBM) is further added at oneend of the conductive trace 108 for receiving the bump 120. Conductivetrace 108 is metallic material such as gold, silver, copper, and alloythereof. Dielectric materials like a rubber or a polymer material suchas epoxy, polyimide, polybenzoxazole (PBO), and the like are disposedover the substrate 105 in order to provide electrical isolation orprotection from environment moisture. For some embodiments as in FIG. 1,the dielectric materials includes a first PBO 112 between thepassivation 110 and the conductive trace 108; and a second PBO 114disposed on the conductive trace 108.

Another independent semiconductor device is a semiconductor die 140which is connected with another end of the bump 120. In someembodiments, the semiconductor die 140 is surface mounted to thesubstrate 150 and bonded with the substrate 150 through the bump 120. Aconductive pad 142 on an active surface 147 of the semiconductor die 140provides a site to receive the bump 120 so as to build communicationpath between the semiconductor die 140 and the substrate 150. Thesemiconductor die 140 has several sub-components such as MOSFET, backendinterconnection and dielectric layers. In some embodiments, thesemiconductor die 140 includes transistors, resistors, and/orcapacitors, which may be interconnected through an interconnect layer toadditional integrated circuits.

In some embodiments, the conductive pad 142 is connected with aninterconnection such as conductive plugs of the semiconductor die 140.In some embodiments, the conductive pad 142 is a copper pillar extendingfrom a contact pad 144. In some embodiments, the conductive pad 142 is aunder bump metal (UBM). In some embodiments, there is an extraconductive interconnect between the contact pad 144 and the conductivepad 142.

In some embodiments, lead-free solder compositions is used to form bump120. The lead-free solder includes tin, copper and silver (typically95.5% by weight tin, 4% by weight silver and 0.5% by weight copper).Bismuth may also be used together with tin, antimony and silver in arange of approximately 1.0% to 4.5% by weight. Solder material 36 can bemetal or electrically conductive material, e.g., Sn, lead (Pb), Au, Ag,Cu, zinc (Zn), bismuthinite (Bi), and alloys thereof, with an optionalflux material.

A molding compound 130 is filled in a gap between the substrate 150 andthe semiconductor die 140. Molding compound 130 includes variousmaterials, for example, one or more of epoxy resins, PBO, phenolichardeners, silicas, catalysts, pigments, mold release agents, and thelike. Material for forming a molding compound has a high thermalconductivity, a low moisture absorption rate, a high flexural strengthat board-mounting temperatures, or a combination of these.

A metal structure is on a surface of the molding compound 130 andlocated proximal to the semiconductor die 140. The metal structure hasan active metal structure 160-a connected to one end of a conducive plug135 in the molding compound 130. The conducive plug 135 is connected toa conductive trace 108 on the substrate 150 at the other end. Anelectrical current is able to travel between the active metal structure160-a and the substrate 150, and therefore an external device other thanthe three dimensional semiconductor structure 100 is electricallycoupled with the substrate 150 through the active metal structure 160-aand the conductive plug 135. In some embodiments, the external device isan electronic device. As used herein, a component is “active” means thatthe component is on an electric current path and able to provideelectric communication when the semiconductor structure 100 is inoperation.

Comparing to the active metal structure 160-a, a dummy portion 160-d ofthe metal structure (or called dummy metal structure hereinafter) is notelectrically connected with any active component in the structure 100.The dummy metal structure 160-d is only disposed on a passive surface148, which is also a backside of the semiconductor die 140 and oppositeto the active surface of the semiconductor die 140. When the threedimensional semiconductor structure 100 is in operation, heat generatedin semiconductor die 140 is dissipated from the passive surface 148 bythe dummy metal structure 160-d. For some embodiments as in FIG. 1, thedummy metal structure 160-d has a similar shape as the active metalstructure 160-a.

Both metal structures, 160-a and 160-d, are in a same level of the threedimensional semiconductor structure 100. In some embodiments, the activemetal structure 160-a and dummy structure 160-d act as a redistributionlayer (RDL). However, the dummy structure 160-d is not electricallyconnected with any circuitry inside or outside the three dimensionalsemiconductor structure 100. Each of the active or dummy structures isfurther connected with a bump. For example, the active metal structure160-a is connected with a bump 126 and the dummy metal structure 160-dis connected with a bump 125. A bump connected with an active metalstructure 160-a is also named as an active bump, and a bump connectedwith a dummy metal structure 160-d is also named as a dummy bump. Bumpsconnected with metal structures 160-a and 160-d are terminals of thethree dimensional semiconductor structure 100 that are designed to be incontact with an external electronic device, such as anothersemiconductor die or a printed circuit board (PCB). However, a dummybump like 126 is only designed to be in contact with some electricalisolated conductive features on the external device. No electricalcurrent travels through the dummy bump 125 when the three dimensionalsemiconductor structure 100 is in operation.

When the three dimensional semiconductor structure 100 is in operation,heat is generated inside the structure 100. The semiconductor die 140,which includes high density of devices, is one of the heat sources. Theheat generated from the semiconductor die 140 needs to be dissipated inorder to avoid malfunction or breakdown. In the present disclosure, heatgenerated in the semiconductor die 140 is dissipated to the dummy metalstructure 160-d from the passive surface 148. Because the passivesurface 148 is directly contacting with the dummy metal structure 160-d,temperature gradient between the semiconductor die 140 and the dummymetal structure 160-d drives heat into the dummy metal structure 160-dthrough the passive surface 148.

Further, dummy metal structure 160-d transfers received heats into dummybump 125. Because dummy bump 125 is fabricated with metallic materialand therefore heats on the dummy structure 160-d is dissipated by thedummy bump 125 effectively. Thus, the dummy structure 160-d and thedummy bump 125 together forms a heat dissipation channel for thesemiconductor die 140. One of the advantages to use a dummy bump forheat dissipation is that the dummy bump has a three dimensional surface,such that heats can be efficiently transferred into ambient surroundingthe three dimensional surface by the dummy bump.

FIG. 2 is an enlarged view of the dummy metal structure 160-d and dummybump 125 as in FIG. 1. The dummy metal structure 160-d has a portion160-d 1 being in contact with the passive surface 148 of thesemiconductor die 140. In FIG. 2, the portion 160-d 1 is a recessedportion and surrounded by a dielectric layer 152. The dummy structure160-d has a portion 160-d 2 extending from the recessed portion 160-d 1to be over a top surface 152 a of the dielectric 152. Another portion160-d 3 is connected with portion 160-d 2 and has a flat surface forreceiving a dummy bump 125. In some embodiments, the portion 160-d 3 isan UBM with a recessed top surface for receiving dummy bump 125. In someembodiments, the UBM includes multiple metallic layers, and is formedwith a conductive material such as gold, silver, copper, nickel,tungsten, aluminum, and/or alloys thereof. Heat generated in thesemiconductor die 140 is firstly transferred to the recessed portion160-d 1 and then being conducted into portions 160-d 2 and 160-d 3.After that, portion 160-d 3 transfers the heat into dummy bump 125. Theheat transferred into dummy bump 125 is further dissipated into ambientthrough a three dimensional surface 125 a. Dummy metal structure 160-dincludes be Al, Cu, Sn, Ni, Au, Ag, or other suitable conductivematerial.

A dielectric layer 154 is disposed over the dielectric 152 to isolate aportion of the dummy metal structure 160-d from electrical shortage ormoisture. The dielectric layer 154 also covers the recessed portion160-d 1 and surrounds portion 160-d 2. The dielectric layer 154 includesrubber or polymer material such as epoxy, polyimide, polybenzoxazole(PBO), and the like.

The dummy bump 125 can be connected with a heat sink 300 at one end asshown in FIG. 3. The heat sink 300 is designed to keep a temperatureconstantly lower than the dummy bump 125. Temperature gradient betweenthe dummy bump 125 and heat sink 300 drives heats in dummy bump 125toward the heat sink 300. In FIG. 4, a heat conductive trace 402 on anexternal device such as PCB 404 acts as a heat sink to carry heats awayfrom dummy bump 125. In some embodiments, the trace 402 is a dummyelectrical trace of the PCB 404. The trace 402 is composed with varioushigh thermal conductivity materials such as metal, grapheme, carbonnano-tube, diamond, etc.

FIG. 5 is a flowchart of a method 500 for fabricating a semiconductorstructure according to various aspects of the present disclosure.Referring also to FIGS. 6A to 6K, illustrated are different views of asemiconductor structure at various stages of fabrication according tothe method 500 of FIG. 5. In some embodiments, the semiconductorstructure is a three dimensional stack. It should be noted that part ofthe semiconductor structure may be fabricated with a wafer level packageprocess flow. Accordingly, it is understood that additional processesmay be provided before, during, and after the method 500 of FIG. 5. Itis understood that FIGS. 6A to 6K have been simplified for the clarityto better understand the inventive concepts of the present disclosure.The semiconductor structure may be fabricated to become a fan-in orfan-out structure. Some metallization process may be implemented to forminterconnections provided as communication signal traces of thesemiconductor dies.

The method 500 includes operation 502 in which a substrate is provided.The method 500 continues with operation 504 in which a circuitry isformed on a top surface of the substrate. The method 500 continues withoperation 506 in which a semiconductor die is flipped and bonded withthe circuitry through a bump. The method 500 continues with operation508 in which a conductive plug is formed and a first end of theconductive plug is connected with the circuitry. The method 500continues with operation 510 in which a passive surface of thesemiconductor die and a second end of the conductive plug are exposed.The method 500 continues with operation 512 in which a metal structureis formed on the backside of the semiconductor die and the second end ofthe conductive plug.

Elements with same labeling numbers as those in FIG. 1 to FIG. 4 arepreviously discussed with reference thereto and are not repeated herefor simplicity.

In FIG. 6A, a substrate 105 is provided. The substrate 105 has a topsurface 105 a and a bottom surface 105 b. A circuitry is formed on thetop surface 105 a as in FIG. 6B. The circuitry includes some metal pads106 located directly on the top surface 105 a. A metal conductive trace,such as PPI 108 is connected with a metal pad 106 directly. Somedielectric materials are inserted between different conductive materiallayers. A dielectric layer 110, which is also a passivation of thesubstrate 105 is disposed to surround the metal pad 106. In someembodiments, the metal pad 106 is formed during a top metal etchoperation. Metal pad 106 is formed along with top metal patterning. Thedielectric layer 110 is disposed thereafter to cover the metal pad 106and an extra etch operation is introduced to remove a portion of thedielectric 110 and expose the metal pad 106.

Another dielectric 112 is disposed on the dielectric 110 and metal pad106. In some embodiments, the dielectric 112 is a PBO layer and the PBOis spin coated on the dielectric 110. Opening like 112 a is formed in aphoto lithography operation to expose the metal pad 106. In someembodiments, the PBO is replaced with other dielectric material such assilicon oxide, silicon nitride, or oxynitride, and an etch operation isadopted to form the opening 112 a. Conductive film is further disposedon the PBO and filled in the opening 112 a. In some embodiments, theconductive film is metal and formed with a vapor deposition, sputter, orother methods. The conductive film is then etched to form conductivetrace 108 on the dielectric 112.

In FIG. 6C, a dielectric 114 is further disposed on the dielectric 112and conductive trace 108. In some embodiments, both dielectric 112 anddielectric 114 are formed with PBO. Dielectric 112 is called PBO1, anddielectric 114 is called PBO2. Some openings 114 a are formed by a photolithography process to expose a portion of conductive trace 108.

Conductive plugs 135 are formed on some exposed conductive trace 108 asin FIG. 6D. In some embodiments, a patterned photo resist is disposed onthe dielectric 114 with some openings. In some embodiments, a platingoperation includes forming a physical vapor deposition (PVD) seed layerin the openings and electroplating a metallic film on the seed layer. Insome embodiments, a plating operation is a sputtering process. Afterfilling the opening in the patterned photo resist, the patterned photoresist is removed and leaves conductive plug 135 standing over thesubstrate 105 as in FIG. 6D.

In FIG. 6E, a semiconductor die 140 is flipped and bonded on someconductive traces 108 with bumps 120. In some embodiments, bumps 120 aredisposed and reflowed on the semiconductor die 140 prior to bonding thesemiconductor die 140 on the conductive traces 108. In some embodiments,bumps 120 is formed on corresponding conductive traces 108 and thenbonded the semiconductor die 140 on the bump 120.

In FIG. 6F, molding compound 130 is used to filled in a gap betweensemiconductor die 140 and substrate 150. The molding compound 130 alsosurrounds conductive plugs 135 and semiconductor die 140. In someembodiments as in FIG. 6F, molding compound 130 also covers conductiveplugs 135 and semiconductor die 140. An additional operation is neededto remove a portion of molding compound 130 in order to expose a passivesurface of the semiconductor die and one end of the conductive plug 135.As in FIG. 6G, one end 135 b of the conductive plug 135 and a passivesurface 148 of the semiconductor die 140 are exposed. In someembodiments, the molding compound 130 is cured to increase the hardnessand then grounded to expose the passive surface 148 and end 135 b of theconductive plug 135.

After exposing the passive surface 148 and conductive plug 135, adielectric layer 152 is disposed on the molding compound 130 and passivesurface 148 as in FIG. 6H. In some embodiments, the dielectric layer 152if formed by spin coating with PBO or other polymeric materials. In someembodiments, the dielectric layer 152 is formed with vapor deposition.Several openings are formed in the dielectric layer 152. Some of theopenings are designed to expose end 135 b of the conductive plug 135,and some of the openings are designed to expose a portion of the passivesurface 148.

Metal structures like 158 and 159 are filled into the openings. Activemetal structure 158 is disposed on a corresponding conductive plug 135in order to provide communication between an external electronic deviceand the substrate 105. Dummy metal structure 159 is formed to be incontact with the passive surface 148 for heat dissipation. In someembodiments, both active and dummy structures are formed during sameoperations. The operations include forming a conductive film on thedielectric 152 with electroplating and then pattering the conductivefilm to form the layout of metal structures 158 and 159.

In FIG. 6I, another dielectric 154 is disposed on dielectric 152 andmetal structures 158 and 159 with coating or vapor deposition. Severalopening 154 a are formed to expose a portion of metal structures 158 and159. In some embodiments, the dielectric 154 is formed with PBO or otherpolymeric materials. In some embodiments, the dielectric 154 is formedwith silicon oxide, silicon nitride, or other suitable dielectricmaterials.

FIG. 6J is an operation of the present disclosure. A conductive materialis filled into the openings 154 a and covers the dielectric 154. Asimilar patterning operation as in FIG. 6H is adopted to remove aportion of the conductive material to form active metal structures 160-aand dummy metal structure 160-d as in FIG. 1.

In some embodiments, bumps are further disposed on the metal structures160-a and 160-d. As in FIG. 6K, bumps like 125 and 126 are placed on themetal structures 160-a and 160-d. A dummy bump 125 is disposed on acorresponding dummy metal structure 160-d and an active bump 126 isdisposed on a corresponding active metal structure 160-a. The bumps aredisposed with various methods such as ball drop, stencil, pasting, orelectroplating, etc. A reflow operation is also introduced to improvethe wettability between the bumps and metal structures. A semiconductorstructure 100 as in FIG. 1 is formed.

A semiconductor structure includes a substrate and a circuitry on thesubstrate. The semiconductor structure also includes a metal structureelectrically coupled with the circuitry through a conductive plug. Insome embodiments, the semiconductor structure includes a semiconductordie bonded with the substrate with a bump via a conductive pad on anactive surface of the semiconductor die, and a passive surface of thesemiconductor die contacting a dummy portion of the metal structure,wherein the passive surface is opposite to the active surface. Moreover,the semiconductor structure includes a molding compound filling a gapbetween the substrate and the active surface of the semiconductor dieand surrounding the conductive plug.

In some embodiments, the semiconductor structure further includes adummy bump connected to the dummy portion of the metal structure,wherein the dummy bump is configured to dissipate heat from the passivesurface. The metal structure of the semiconductor structure includes aredistribution layer connecting to one end of the conductive plug.

In some embodiments, the metal structure of the semiconductor structurethe metal structure includes an under bump metal (UBM) for receiving thedummy bump. In some embodiments, the semiconductor structure includes anactive bump connected to an active portion of the metal structure. Insome embodiments, the circuitry on the substrate includes a postpassivation inductor (PPI) and the PPI is connected to one end of theconductive plug.

In some embodiments, the conductive pad on the active surface of thesemiconductor die is an under bump metal (UBM), and the conductive padis connected to an interconnection of the semiconductor die.

A semiconductor structure includes a three dimensional stack including afirst semiconductor die and a second semiconductor die. The secondsemiconductor die is connected with the first semiconductor die with abump between the first semiconductor die and the second semiconductordie. The semiconductor structure includes a molding compound between thefirst semiconductor die and the second semiconductor die. A firstportion of a metal structure over a surface of the three dimensionalstack and contacting a backside of the second semiconductor die and asecond portion of the metal structure over the surface of the threedimensional stack and configured for electrically connecting the threedimensional stack with an external electronic device.

In some embodiments, the semiconductor structure includes a conductiveplug between the metal structure and the first semiconductor die. Insome embodiments, the semiconductor structure includes a dummy bumpconnected with the first portion of the metal structure, wherein thedummy bump is configured to connect with a dummy pattern external to thethree dimensional stack.

In some embodiments, the semiconductor structure includes a plurality ofbumps configured for electrically connected to a printed circuit board(PCB). In some embodiments, the semiconductor structure includes a PPIon the first semiconductor die and electrically coupled to the firstsemiconductor die.

A method of manufacturing a semiconductor structure includes severaloperations. One of the operations is providing a substrate. One of theoperations is forming a circuitry on the substrate. One of theoperations is flip bonding a semiconductor die with the circuitry with abump. One of the operations is forming a conductive plug with a firstend connected with the circuitry. One of the operations is exposing apassive surface of the semiconductor die and a second end of theconductive plug. One of the operations is forming a metal structure onthe backside of the semiconductor die and the second end of theconductive plug.

In some embodiments, the method includes disposing a molding compound onthe substrate to surround the semiconductor die and the conductive plug.

In some embodiments, the method includes performing a grinding operationto remove a portion of the molding compound to expose a passive surfaceof the semiconductor die and a second end of the conductive plug.

In some embodiments, the method includes disposing a dummy bump on aportion of the metal structure.

In some embodiments, the method includes forming a PPI in the circuitry.

In some embodiments, the method includes forming a patterned photoresist on the substrate for forming the conductive plug.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, and composition of matter, means, methods and stepsdescribed in the specification. As those skilled in the art will readilyappreciate form the disclosure of the present disclosure, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present disclosure.

Accordingly, the appended claims are intended to include within theirscope such as processes, machines, manufacture, and compositions ofmatter, means, methods or steps. In addition, each claim constitutes aseparate embodiment, and the combination of various claims andembodiments are within the scope of the invention.

What is claimed is:
 1. A method of manufacturing a semiconductorstructure, comprising: bonding a semiconductor die to a substrate, thesubstrate having circuitry thereon; forming a conductive plug with afirst end connected to the substrate; exposing a passive surface of thesemiconductor die and a second end of the conductive plug; and forming ametal structure on the passive surface of the semiconductor die and thesecond end of the conductive plug, the metal structure comprising anactive portion and a dummy portion, the active portion electricallycoupled with the circuitry through the conductive plug, the dummyportion not being electrically coupled with any circuitry, the activeportion and the dummy portion being on a same level of the metalstructure.
 2. The method of claim 1, further comprising disposing amolding compound on the substrate to surround the semiconductor die andthe conductive plug.
 3. The method of claim 2, further comprisingperforming a grinding operation to remove a portion of the moldingcompound to expose the passive surface of the semiconductor die and thesecond end of the conductive plug.
 4. The method of claim 1, furthercomprising disposing a dummy bump on a portion of the metal structure.5. The method of claim 1, the substrate comprises a post-passivationinterconnect (PPI).
 6. The method of claim 1, wherein forming theconductive plug comprises forming a patterned photo resist on thesubstrate.
 7. A method of forming a semiconductor device, the methodcomprising: forming a conductive pillar on a substrate; bonding a firstintegrated circuit to the substrate; forming a molding compound betweenthe first integrated circuit and the conductive pillar; and forming ametal structure over the molding compound and the first integratedcircuit, wherein the metal structure comprises a dummy portion and anactive portion, the active portion being electrically coupled to theconductive pillar, the dummy portion being laterally over the firstintegrated circuit, wherein the dummy portion is not electricallycoupled to the first integrated circuit or the substrate.
 8. The methodof claim 7, wherein the substrate comprises a second integrated circuit.9. The method of claim 7, wherein forming the conductive pillar isperformed before bonding the first integrated circuit to the substrate.10. The method of claim 7, further comprising thinning the moldingcompound to expose first integrated circuit.
 11. The method of claim 7,wherein the dummy portion directly contacts the first integratedcircuit.
 12. The method of claim 7, further comprising forming anexternal connection to the dummy portion.
 13. The method of claim 12,wherein the external connection comprises a solder connection.
 14. Themethod of claim 7, wherein bonding the first integrated circuit to thesubstrate comprises flip-chip bonding.
 15. A method of forming asemiconductor device, the method comprising: forming a first insulatinglayer over a molding compound and a first integrated circuit, a passivesurface of the first integrated circuit and a conductive plug beingexposed in the first insulating layer; forming a dummy conductiveportion over the first insulating layer, the dummy conductive portionextending through a first opening in the first insulating layer; formingan active conductive portion over the first insulating layer, the activeconductive portion extending through a second opening in the firstinsulating layer, the active conductive portion being electricallycoupled to the conductive plug; forming a first conductive externalconnector electrically coupled to the dummy conductive portion; andforming a second conductive external connector electrically coupled tothe active conductive portion.
 16. The method of claim 15, wherein thedummy conductive portion directly contacts the first integrated circuit.17. The method of claim 15, prior to forming the first insulating layer,further comprising electrically coupling the first integrated circuit toa substrate.
 18. The method of claim 17, wherein the substrate comprisesa second integrated circuit.
 19. The method of claim 15, wherein thefirst conductive external connector and the second conductive externalconnector comprise solder connections.
 20. The method of claim 15, priorto forming the first insulating layer, further comprising: forming themolding compound over the first integrated circuit and the conductiveplug; and thinning the molding compound to expose the first integratedcircuit and the conductive plug.